“严重犯罪”和“重罪”严格意义上来说，区别还挺大的。

“严重犯罪”在美国指违背公共道德的不名誉罪，尤指参议院认为构成总统、副总统或其他文职官员不适合担任行政职务，应受到弹劾的适当理由的犯罪，如叛国、贿赂等。严格来说不同于重罪〔felony〕。

在国内，“严重犯罪”从字面可理解为性质严重、情节恶劣、对社会造成重大危害的犯罪，包括公安机关、国家安全机关、检察机关侦查的各类重特大犯罪。这是对此广义的解释。但从历次政法机关在论述社会治安形势和开展“严打”斗争使用该语时，是有特指的，并不象字面理解那么宽泛，可解释为由公安机关和国家安全机关侦查、严重危害社会治安秩序、宣告刑在五年有期徒刑以上的刑事犯罪。这是对“严重刑事犯罪”的狭义解释。

“严重犯罪”在《元照英美法词典》中的英文是high crimes。具体可参考以下双语例句：

The President, Vice President and all Civil Officers of the United States, shall be removed from Office on Impeachment for and Conviction of, Treason, Bribery, or other high Crimes and Misdemeanors.

美国总统、副总统及所有文职官员如因叛逆、贿赂或其他严重罪行或行为失当而被弹劾并且定罪，即被罢免。

The President, Vice President and all Civil Officers of the United States, shall be removed from Office on Impeachment for and Conviction of, Treason, Bribery, or other high Crimes and Misdemeanors.

美国总统、副总统及所有文职官员如因叛逆、贿赂或其他严重罪行或行为失当而被弹劾并且定罪，即被罢免。

此外，也有serious crimes等其他译法，可参考如下例句：

Due to the upsurge in serious and high-profile crimes attributed to illicit drug activities, which undermine development and stability in Africa, a study on the drug situation in African correctional facilities was carried out by the Institute in 2011, starting with the East African subregion.

由于非法毒品活动导致的严重犯罪和重大刑事案件突增，破坏了非洲的发展和稳定，研究所于 2011 年从东非分区域开始，对非洲管教机构内的毒品情况进行了研究。

Life imprisonment is imposed for the commission of particularly serious crimes against the life, honour or dignity of a person or for actions directe at the partial or total destruction of national, ethnic or religious groups.

对个人的生命、荣誉和尊严实施特别 严重犯罪 或 对 国家、种族和宗教团体 实施部分或全部破坏行为的人将被判处终身监禁。

To fight impunity Norway had recently strengthened the National Authority for Prosecution of Organized and Serious Crimes.

为打击有罪不罚现象，挪威最近加强了国家有组织犯罪和严重犯罪检察署。

“重罪”是指在普通法中，指涉及没收罪犯的土地与财产归国王所有，并根据其犯罪行为的轻重另行处以死刑或其他刑罚的严重犯罪。在传统上，叛逆罪〔treason〕被划入重罪范畴之中。1967年，英国完全取消了重罪与轻罪的划分，重罪一词不再使用。

重罪与轻罪之分已被可逮捕罪〔arrestable offence〕与不逮捕罪〔non-arrestable offence〕之分取代。在美国，重罪是指对某些比较严重罪行的总称。某些州则据如下标准进行犯罪分类：１罪犯关押地——是州监狱〔prison〕还是教养收容所〔penitentiary〕；或２可能最长刑期。许多州的制定法都规定重罪是指应判处1年以上监禁或死刑的犯罪。美国联邦和许多州的刑法典都规定了重罪种类或级别及与之相适应的刑罚。重罪犯可能丧失许多轻罪犯不会丧失的权利，如选举、律师执业、就任政府官员、做陪审员等。

“重罪”的英文表达为felony，释义如下：

A felony is traditionally considered a crime of high seriousness, whereas a misdemeanor is regarded as less serious. The term "felony" originated from English common law (from the French medieval word "félonie") to describe an offense that resulted in the confiscation of a convicted person's land and goods, to which additional punishments including capital punishment could be added; other crimes were called misdemeanors. Following conviction of a felony in a court of law, a person may be described as a felon or a convicted felon.

双语例句参考如下：

Article 103 of the Law stipulates that the deputy public prosecutor may, in felony cases and in the interests of expediting the investigation, decide to prohibit communication with the suspect for a period of not more than 10 days, renewable only once.

第 103 条规定，副检察官可在重罪案中为加快调查进度之故决定禁止与羁押中的嫌疑人沟通，期限不超过10天，只能延期一次。

The members were also informed by one NGO that in many states a felony conviction disqualifies a person from being eligible for jury duty.

有一个非政府组织还告诉工作组成员说，在许多州，一个人判过重罪的，就没有资格参加陪审团工作。